Necropsies of the moribund/deceased mice revealed that a fraction of Asxl2+/− and Asxl2−/− BM recipients had splenomegaly, severe anemia, decreased platelet counts and significantly higher percentages (>20%) of cKit+ cells in the BM (Fig. 4d,e and Supplementary Fig. 7c,d). The gene discussed is ASXL2; the disease is Splenomegaly.